Flash lamp



March 13, 1956 D. CROPP 2,737,798

FLASH LAMP Filed Aug. 7, 1952 INVENTOR. 0A W0 C/eoPP BY %Z a W ATTOR/VL'Y United States Patent FLASH LAMP David Cropp, Warren, Pa., assignor to Solar Electric Corporation, Warren, Pa., a corporation of Pennsylvania Application August 7, 1952, Serial No. 303,143

Claims. (Cl. 67-31) with lead-in wires positioned therebetween, whereby said wires become sealed through a glass or plastic wall resulting from the fusion of said flared tube and exhaust tube around the said wires, and whereby a lamp stem assembly is produced.

Thereafter, the stem assembly must be allowed to cool off so that a filament can be mounted across the lead-in wires and a heat sensitive primer or ignition material applied to the filament.

The need for this procedure has been a critical requisite because the ignition material applied to the filament is so heat sensitive that if the exhaust tube and flared tube had been fused together by heating after the application of the ignition material, the heat conducted by the leadin wires to he filament and ignition material would burn up or ignite the ignition material thereby rendering the assembly useless. i

, However, the aforesaid procedure is substantially timeconsuming and otherwise necessitates a stem assembly which requires special stern making apparatus representing a substantial portion of the cost of manufacturing photo flash lamps.

It is an object of the present invention to provide an economical. photo flash lamp. It is another object of the present invention to provide a photo flash lampby eliminatingcertain costly structures heretofore considered essential. It is a further object of the present invention to provide a photo flash lamp adapted to be manufactured more automatically than heretofore. Other objects and advantages of the present invention will become apparent from the description hereinafter following and the draw ings forming a part hereof, in which: i

Fig. 1 illustrates a partly sectional and partly elevational view of a conventional assembly used in the manufacture of photo flash lamps,

Fig. 2 illustrates a partly sectional and partly eleva tional view of a stem assembly combining a conventional structure-'witha new component in accordance with the present invention,

Fig. 3 illustrates an enlarged elevational view of a portion of a structural component according to the present invention, and

Fig. 4 illustrates a partly sectional and partly elevational view of a photo flash lamp as a preferred form of the present invention.

The present invention relates to photo flash lamps com- 2,737,798 Patented Mar. 13, 1956 prising a transparent envelope containing a light-emitting combustible material located on a fine filament and which is energizable by lead wires conducting electrical energy to said filament through the wall of said envelope, and said lead wires being particularly adapted to permit lamp envelopes to be made of smaller size than heretofore, to lower the cost of manufacture by eliminating the need of costly lamp stems, and to permitthe actual glass or plastic sealing around the lead wires to take place after the ignition material has been applied to a fine filament without heating said ignition material to its combustible temperature.

According to Fig. 1, the conventional photo flash lamp is manufactured by first heating together a piece of flared glass or plastic tubing 1 and a glass or plastic exhaust tube 2 with lead-in wires 3 and 4 positioned therebetween,

= whereby said wires become sealed through a glass or plastic wall resulting from the fusion of the flared tubing 1 and exhaust tube 2 around the wires 3 and 4, and whereby a lamp stem assembly is produced. After the completion of the stem assembly the filament 5 is mounted as shown and a heat sensitive primer or ignition material 6 is applied to the filament. Thereafter the flared portion of the flared tubing 1 is heat-sealed to the envelope 7. Some intermediate steps such as filling the envelope with combustible metal strands, etc., and subsequent steps such as exhausting the envelope or filling with a combustion supporting gas, are well-known in the art.

' it is, therefore, apparent that the description relating to and the structure illustrated as Fig. 1 sets forth a conventional photo flash lamp.

In order to accomplish the objects of the present invention, I deviate from conventional procedure at least in part, and specifically with regard to the lead-in wires, whereby various time-consuming manufacturing steps are eliminated an a more automatic manufacturing procedure is made possible.

Fig. 2 illustrates a new type of lead-in wires in accordance with the present invention and in combination with otherwise conventional structures.

' The lead-in conductors or wires 8 and 9 comprise essentially a structure whereby actual glass sealing around the ence numerals 10, 11, 12 and 13.

, ,While it has'been found helpful to decrease the heat conductivity of the lead wires by resorting to low conductiv'e metalcomposition, e. g. low conductive iron, this has not been -adequate to keep the primer from being ignited in many instances. It has also been found helpful to decrease the heat conductivity of the wires by providing a wire construction comprising a wire formed of two or more conductors or wires 14 and 15' of dissimilar composition joined together longitudinally thereof by welding, whereby one of the wire portions may be composed of a metal better adapted for sealing to glass or plastic than another wire portion for providing a hermetical glass to metal seal, etc.

However, in order to insure against the heating of the primer 6 to its combustion temperature, the constrictions or reduced portions above set forth are critical embodiments since they provide a sufiicient resistance to the conduction of heat to prevent the primer from reaching its combustion temperature. Such constrictions or necks, obviously characterized as portions of lesser cross-sectional area than the other portions of the wire, may be applied to wires comprising a composite of dissimilar metals, or to wires of single metal composition, and the constrictions are essentially provided to that portion of the wire which is positioned within the envelope of the lamp between the envelope wall and the filament 5 bridging the wires 8 and 9.

Fig. 3 illustrates an enlarged view of the wire 14 shown in Fig. 2 and particularly illustrates a neck 12v having preferably the form of a concave surface of revolution, e. g. a reduced portion of a wire formed by rolling a neck in the wire, which provides a distance d or length great enough so that no substantial radiation c onductivityfwill occur from one unnecked portion of the wire to the other unnecked portion, i. e. a distance d at least equal to or greater than the depth of the constriction.

However, the cross section of the necked or reduced portion of the conductor itself need not be circular since other neck and wire shapes such as rectangular or triangular are contemplated and formed by pressing, etc., to combine minimum conductivity of heat with maximum physical strength of the conductor.

Fig. 4 illustrates a preferred modification of the present invention and particularly a stemless butt-sealed lamp construction to which the lead-in conductors 8 and 9 are especially applicable and which otherwise could not be produced successfully without the use of the special leadin conductors according to the present invention. preferred modification the lamp is constructed by pressing and flattening an open portion of the envelope 16, at,

location 17, around the constricted lead-in wires 8 and 9 on which the filament 5 and ignition material 6 are mounted prior to a sealing operation.

It is apparent that such a butt-sealing operation enables the manufacture of smaller sized lamps, since specialstem structures are thereby eliminated, and which lamps cornprise all essential embodiments for enabling the lamp to operate as a photo flash lamp.

The present invention is not to be construed as limiting with regard to the particular structures herein illustrated since the scope of the invention is generic to the lead-in conductors according to the present invention for use in lamps and functioning to safeguard a heat susceptible member associated with or in thermal contact with, said conductors against deleterious conducted heat.

What I claim is:

1. A photo flash lamp comprising a light transmissive envelope, lead-in wires sealed through the wall of said en;

velope, an electricaly conductive filament bridging said wires within said envelope, a heat sensitive cornbhstible material contacting said filament, said lead-in wires being each provided with at least one constriction between the envelope wall and the said filament, said constrietion b. e ing. p r l o u e h nduct n of hea hr ugh said.

wire.

A photo flash mp mpr sing a li ht t an missi envelope, lead-in wires sealed through the wall of said nvelope, n l lly c n u tive fi am nt bridg ng said wires within said envelope, a heat sensitive corn In thisv bustible material contacting said filament, said lead-in wires being each provided with at least one neck having a cross-section area less than that of said conductor and located between the envelope wall and the said filament, said neck having a length at least equal to the depth of the constriction of said wire formed by said neck, said neck being operable to reduce the conduction of heat through said wire.

3. A photo flash lamp comprising a light transmissive envelope, lead-in wires sealed through the wall of said envelope, an electrically conductive filament bridging said wires within said envelope, a heat sensitive combustible materialcontacting said filament, said lead-in Wires being each provided with at least one constriction between the envelope wall and the said filament, said constriction being operable to reduce the conduction of heat through said wire, and said envelope being a stemless envelope having the lead-in wires sealed directly through the envelope wall.

4. The method of providing a photo flash lamp com? prising forming at least one constriction in each of a pair of lead-in wires, bridging the lead-in wires with an electrically conductive filament, applying a heat sensitive combustible material in contact with said filament, inserting said lead-in wires through an opening of a light transmissive envelope so that said filament, combustible material and constriction lie within the envelope, and heat sealing the open portion of said envelope over said wires below said constrictions.

5. The method of providing a photo flash lamp comprising forming at least one constriction in each of a pair of lead-in wires, positioning said lead-in wires between a flared tubing and an exhaust tube, fusing said flared tub-.

ing and said exhaust tube around said wires below said constriction thereby sealing said wires between said flared tubing and said exhaust tube, bridging the lead-in wires above said construction with an electrically conductive filament, applying a heat sensitive combustible material in contact with said filament, inserting said lead-in wires through an opening of a light transmissive envelope so that said filament, combustible material and constriction lie within said envelope, and heat sealing the open portion of said envelope to said flared tubing.

References Cited in the file of this patent UNITED STATES PATENTS 1,453,595 Mitchell May 1, 1923 1,681,329 Fitch Aug. 21, 1928 2,115,147 Marshall Apr. 26, 1938 2,270,162 De Margitta Jan. 13, 1942 2,291,983 Pipkin Aug. 4, 1942 2,359,483 Kuebler Oct. 3, 1944 2,367,583 Hopkinson s Jan. 16, 1945 2,398,593 Mouromtzefi Apr. 16, 1946 

